1. Field of the Invention
The present invention generally relates to sealing devices. More specifically, the present invention is drawn to a hot gas seal for a conduit or the like, which conduit is inserted in a wall of a heat recovery steam generator or the like.
2. Description of the Related Art
Large diameter conduits are utilized to effectively and efficiently transport fluids (gases or liquids) to and from pressure vessels such as heat recovery steam generators. These large conduits must penetrate the walls of the pressure vessel and enter the vessel through a gap formed through the casing of the vessel. Usually, because of thermal expansion and contraction, the conduits are subject to lateral and axial movement. This movement plays havoc with the hot gas seals installed on the conduit and casing, eventually causing the seals to fail. Seal failure may require shutdown and replacement, thereby creating downtime, a safety hazard due to leaking gases at very high temperatures and economic losses due to escape of the working fluid. The seal failure is especially pernicious if the lateral movement of the conduit is greater than 2 inches. Currently available commercial seals typically do not accommodate more than 2 inches of lateral movement due to space limitations. Axial and lateral movement must be considered simultaneously. In the related art, this has resulted in seals that are excessively long and/or wide. The art would certainly welcome an effective hot gas seal that could withstand the rigors caused by lateral movement greater than 2 inches and unlimited axial movement with high reliability in a relatively small space.
The related art is rife with means for sealing pipes that penetrate vessel walls. Pertinent examples of such related art are identified and cited in the accompanying IDS. However, none of the identified and cited related art, taken either singly or in combination, is seen to disclose a hot gas expansion seal as will subsequently be described and claimed in the instant invention.